1. Field of the Invention
The present invention relates to a discriminating apparatus for a digital audio broadcasting suitable for application to a receiver for a broadcasting system called a digital audio broadcasting (DAB) established in Europe.
2. Description of the Related Art
As shown in FIG. 6, a digital audio broadcasting, by varying its frequency, is positioned on a plurality of frequency allocations which are arranged at an equal frequency interval. However, the digital audio broadcasting is not always on all of the frequency allocations, but there is such a case where a television broadcasting may be on a part of the frequency allocations. Therefore, it is necessary to determine whether or not there exists a television broadcasting on a certain frequency allocation.
In the above example, under the assumption that a digital audio broadcasting exists on a certain frequency allocation and a received signal is decoded by the synchronization of the DAB signal, it is discriminated whether or not the digital audio broadcasting exists by whether an audio signal can be obtained or not.
It takes several to some 10 frames (a little less than 1 second) to synchronize the DAB signal, and therefore it takes much time to discriminate whether a digital audio broadcasting exists or not on every frequency allocation. This is not practical.